Methods and apparatus for expressing body fluid from an incision

ABSTRACT

A sample of a body fluid such as blood or interstitial fluid is obtained from a body by lancing a portion of a user&#39;s skin, preferably in an area other than a finger tip, to form an incision. After the needle has been removed from the incision, a force is applied to depress the skin in a manner forming a ring of depressed body tissue in surrounding relationship to the incision, causing the incision to bulge and the sides of the incision to open, whereby body fluid is forced out through the opening of the incision. A stimulator member is mounted to an end of a lancet-carrying housing for applying the force. The stimulator member can be movable relative to the housing, and can be either heated or vibrated to promote movement of the body fluid.

PRIOR APPLICATIONS

[0001] This application claims benefit of copending application Ser.Nos. 08/017,133 filed May 17, 1996; 08/019,918 filed Jun. 14, 1996;08/023,658 filed Aug. 1, 1996; 08/025,340 filed Sep. 3, 1996; 08/714,548filed Sep. 16, 1996; and 08/710,456 Sep. 17, 1996; the disclosures ofwhich are incorporated herein by reference.

[0002] The present invention is related to inventions disclosed in thefollowing concurrently filed, commonly assigned U.S. applications: Ser.No. , entitled “Body Fluid sampling Device and Methods of Use” (attorneydocket No. 018176-039); Ser. No. , entitled “Methods and Apparatus forSampling Body Fluid” (attorney docket 018176-057); Ser. No. , entitled“Disposable Element for Use in a Body Fluid Sampling Device” ((attorneydocket 018176-058); and Ser. No. , entitled “Methods and Apparatus forSampling and Analyzing Body Fluid” (attorney docket 018176-059). Thedisclosures of those applications are incorporated herein by reference.

FIELD OF THE INVENTION

[0003] The present invention relates to lancing devices and methods forobtaining samples of blood and other fluids from the body for analysisor processing.

BACKGROUND OF THE INVENTION

[0004] Many medical procedures in use today require a relatively smallsample of blood, in the range of 5-50 μL. It is more cost effective andless traumatic to the patient to obtain such a sample by lancing orpiercing the skin at a selected location, such as the finger, to enablethe collection of 1 or 2 drops of blood, than by using a phlebotomist todraw a tube of venous blood. With the advent of home use tests such asself monitoring of blood glucose, there is a requirement for a simpleprocedure which can be performed in any setting by a person needing totest.

[0005] Lancets in conventional use generally have a rigid body and asterile needle which protrudes from one end. The lancet may be used topierce the skin, thereby enabling the collection of a blood sample fromthe opening created. The blood is transferred to a test device orcollection device. Blood is most commonly taken from the fingertips,where the supply is generally excellent. However, the nerve density inthis region causes significant pain in many patients. Sampling ofalternate site, such as earlobes and limbs, is sometimes practiced toaccess sites which are less sensitive. These sites are also less likelyto provide excellent blood samples and make blood transfer directly totest devices difficult.

[0006] Repeated lancing in limited surface areas (such as fingertips)results in callous formation. This leads to increased difficulty indrawing blood and increased pain.

[0007] To reduce the anxiety of piercing the skin and the associatedpain, many spring loaded devices have been developed. The following twopatents are representative of the devices which were developed in the1980's for use with home diagnostic test products.

[0008] Cornell et al. U.S. Pat. No. 4,503,856 describes a spring loadedlancet injector. The reusable device interfaces with a disposablelancet. The lancet holder may be latched in a retracted position. Whenthe user contacts a release, a spring causes the lancet to pierce theskin at high speed and then retract. The speed is important to reducethe pain associated with the puncture.

[0009] Levin et al. U.S. Pat. No. 4,517,978 describes a blood samplinginstrument. This device, which is also spring loaded, uses a standarddisposable lancet. The design enables easy and accurate positioningagainst a fingertip so the impact site can be readily determined. Afterthe lancet pierces the skin, a bounce back spring retracts the lancet toa safe position within the device.

[0010] In institutional settings, it is often desirable to collect thesample from the patient and then introduce the sample to a test devicein a controlled fashion. Some blood glucose monitoring systems, forexample, require that the blood sample be applied to a test device whichis in contact with a test instrument. In such situations, bringing thefinger of a patient directly to the test device poses some risk ofcontamination from blood of a previous patient. With such systems,particularly in hospital settings, it is common to lance a patient,collect a sample in a micropipette via capillary action and then deliverthe sample from the pipette to the test device.

[0011] Haynes U.S. Pat. No. 4,920,977 describes a blood collectionassembly with lancet and microcollection tube. This device incorporatesa lancet and collection container in a single device. The lancing andcollection are two separate activities, but the device is a convenientsingle disposable unit for situations when sample collection prior touse is desirable. Similar devices are disclosed in Sarrine U.S. Pat. No.4,360,016, and O'Brien U.S. Pat. No. 4,924,879.

[0012] Jordan et al. U.S. Pat. No. 4,850,973 and No. 4,858,607, disclosea combination device which may be alternatively used as a syringe-typeinjection device and a lancing device with disposable solid needlelancet, depending on configuration.

[0013] Lange et al. U.S. Pat. No. 5,318,584 describes a blood lancetdevice for withdrawing blood for diagnostic purposes. This inventionuses a rotary/sliding transmission system to reduce the pain of lancing.The puncture depth is easily and precisely adjustable by the user.

[0014] Suzuki et al. U.S. Pat. No. 5,368,047, Dombrowski U.S. Pat. No.4,654,513 and Ishibashi et al. U.S. Pat. No. 5,320,607 each describesuction-type blood samplers. These devices develop suction between thelancing site and the end of the device when the lancet holding mechanismwithdraws after piercing the skin. A flexible gasket around the end ofthe device helps seal the end around the puncture site until adequatesample is drawn from the puncture site or the user pulls back on thedevice.

[0015] Garcia et al. U.S. Pat. No. 4,637,403 and Haber et al. U.S. Pat.No. 5,217,480, disclose combination lancing and blood collection deviceswhich use a diaphragm to create a vacuum over the wound site.

[0016] Erickson et al. U.S. Pat. No. 5,582,184, describes a means ofcollecting and measuring body fluids. This system uses a coaxial hollowlancet and capillary tube disposed within a spacer member. The spacermember limits the depth of lancet penetration, and compresses bodytissue around the lancet while the lancet is in the skin, for improvingthe flow of interstitial fluid to the incision. However, the incisionmay tend to close around the lancet, thereby limiting the amount of bodyfluid that can be obtained.

[0017] Single use devices have also been developed for single use tests,i.e. home cholesterol testing, and for institutional use to eliminatecross-patient contamination multi-patient use. Crossman et al. U.S. Pat.No. 4,869,249, and Swierczek U.S. Pat. No. 5,402,798, also disclosedisposable, single use lancing devices.

[0018] U.S. Pat. Nos. 5,421,816; 5,445,611 and 5,458,140 disclose, as areplacement for invasive sampling, the use of ultrasound to act as apump for expressing interstitial fluid directly through intact (i.e.,non-lanced) skin. The amount of fluid which can be obtained by way ofsuch non-invasive vibration is minimal, however.

[0019] The disclosures of the above patents are incorporated herein byreference.

[0020] Even with the many improvements which have been made, the painassociated with lancing remains a significant issue for many patients.The need for blood sampling and the fear of the associated pain is alsoa major obstacle for the millions of diagnosed diabetics, who do notadequately monitor their blood glucose due to the pain involved.Moreover, lancing to obtain a blood sample for other diagnosticapplications is becoming more commonplace, and a less painful, minimallyinvasive device is needed to enhance those applications and make thosetechnologies more acceptable.

[0021] An object of the present invention therefore, is to provide adevice and a method for obtaining a sample of bodily fluid through theskin which is virtually pain free and minimally invasive, particularlyby penetrating less sensitive areas of the skin.

[0022] Furthermore, known lancing devices include manually actuablebuttons for triggering the lance-driving mechanism once the user hasplaced the device against his/her skin. Because the user knows theprecise instant when the lancet will be triggered and pain will be felt,there is a tendency for the user to jerk or raise the device at theinstant of triggering, which can lead to inconsistent skin penetration,or possibly no penetration. Therefore, a further object of the inventionis to provide a lancing device which eliminates such a tendency on thepart of the user.

[0023] Therefore, it is another object of the invention to provide alancet carrier which eliminates the above-mentioned shortcomings.

[0024] Another object of this invention is to provide a method which canresult in a sample of either blood or interstitial fluid, depending onthe sample site and the penetration depth utilized. While there are nocommercially available devices utilizing interstitial fluid (ISF) atthis time, there are active efforts to establish the correlation ofanalytes, such as glucose, in ISF compared to whole blood. If ISF couldbe readily obtained and correlation is established, ISF may bepreferable as a sample since there is no interference of red blood cellsor hematocrit adjustment required.

[0025] Another object of this invention is to provide a method which candraw a small but adjustable sample, i.e. 3 μL for one test device and 8μL for another test device, as appropriate.

[0026] Another object of this invention is to provide a method by whichthe drawn sample is collected and may be easily presented to a testingdevice, regardless of the location of the sample site on the body. Thisapproach helps with infection control in that multiple patients are notbrought in contact with a single test instrument; only the samplingdevice with a disposable patient-contact portion is brought to the testinstrument. Alternatively, the disposable portion of a test device maybe physically coupled with the sampler so the sample can be broughtdirectly into the test device during sampling. The test device may thenbe read in a test instrument if appropriate or the testing system can beintegrated into the sampler and the test device can provide directresults displayed for the patient.

[0027] It is a further object of the invention is to provide a devicefor minimally invasive sampling comprising a reusable sampler anddisposable sample lancet and collection device.

SUMMARY OF THE INVENTION

[0028] The present invention involves a method of obtaining a sample offluid from a body. The method comprises applying a skin-lancing mediumagainst a skin surface to form an incision therein, removing theskin-lancing medium from the incision; and thereafter applying a forceto depress the skin in a manner forming a ring of depressed body tissuein surrounding relationship to the incision, causing the incision tobulge and the sides of the incision to open, whereby body fluid isforced out through the opening of the incision.

[0029] The invention also relates to a device for sampling body fluidwhich comprises a housing having an open end, and a skin lancingmechanism for applying a skin-lancing medium against a skin surface toform an incision therein and then remove the skin-lancing medium fromthe incision. A stimulator member is mounted to the housing at the openend thereof for movement relative to the housing. The stimulator memberextends about a longitudinal axis of the housing and is adapted toengage the skin surface to bulge and open the incision in response to apressing of the end face against the skin surface.

[0030] The invention also relates to a device for expressing body fluidfrom a lanced skin surface, which comprises a housing, and a stimulatormechanism mounted to the housing at an end thereof. The stimulatormechanism includes a generally circular array of stimulator elementseach mounted to the housing for movement toward and away from alongitudinal axis of the housing. An actuator is mounted to the housingfor displacing the stimulator elements toward the axis.

[0031] The invention also relates to a device for expressing body fluidfrom a lanced skin surface, which comprises a housing and a stimulatormember mounted on the housing at an end thereof. The stimulator membercomprises a coil spring which is compressible toward the housing inresponse to being pushed against a user's skin in surroundingrelationship to a lanced portion thereof.

[0032] Another aspect of the invention relates to a device forexpressing body fluid from a lanced skin surface which comprises ahousing and a hollow stimulator member mounted at an end of the housingand adapted to engage a user's skin surface in surrounding relationshipto a lanced portion thereof. In order to promote the flow of body fluid,the stimulator member can be heated, or vibrated. If vibrated, thestimulator member applies an ultrasonic frequency to the skin surface.

[0033] The invention also relates to a device for expressing body fluidfrom a lanced skin surface which comprises a housing and a hollowstimulator member mounted at an end of the housing for longitudinalmovement relative to the housing and adapted to contact a user's skinsurface in surrounding relationship to a lanced portion thereof. A motoris mounted in the housing and a reciprocatory mechanism is connected tothe motor to be driven thereby, and is operably connected to thestimulator member for reciprocating the stimulator member along alongitudinal axis of the stimulator member.

BRIEF DESCRIPTION OF THE DRAWING

[0034] The objects and advantages of the invention will become apparentfrom the following detailed description of preferred embodiments thereofin connection with the accompanying drawing in which like numeralsdesignate like elements and in which:

[0035]FIG. 1 is a longitudinal sectional view through a blood samplingdevice according to a first embodiment of the invention, with the lancetcarrier in an unarmed condition;

[0036]FIG. 2 is a view similar to FIG. 1, with the lancet carrier in anarmed condition;

[0037]FIG. 3 is a view similar to FIG. 2 after the lancet carrier hasbeen triggered and a lancet is penetrating the skin;

[0038]FIG. 4 is a fragmentary view similar to FIG. 1 after an incisionhas been formed;

[0039]FIG. 5 is a view similar to FIG. 4 showing a stimulator member ofthe device being depressed to cause the incision to bulge and open;

[0040]FIG. 6 is a view similar to FIG. 5 after a stimulating action hasbeen performed to form a drop of blood at the open end of the incision;

[0041]FIG. 7 is a fragmentary longitudinal sectional view through asecond embodiment of the invention;

[0042]FIG. 8 is a fragmentary longitudinal sectional view taken througha third embodiment of the invention;

[0043]FIG. 9 is a side elevational view of a fourth embodiment of theinvention pressed against a skin surface;

[0044]FIG. 10 is an end view of the device depicted in FIG. 9;

[0045]FIG. 11 is a view similar to FIG. 9 after the device has beencompressed against the skin surface to bulge and open an incision;

[0046]FIG. 12 is an end view of the device in the condition depicted inFIG. 11;

[0047]FIG. 13 is a fragmentary longitudinal sectional view taken througha fifth embodiment of the invention while in a first state of operation;

[0048]FIG. 14 is a view similar to FIG. 13 with the device in a secondcondition of operation;

[0049]FIG. 15 is a fragmentary longitudinal sectional view taken througha sixth embodiment of the invention in a first condition of operationthereof;

[0050]FIG. 16 is a view similar to FIG. 15 with the device in anothercondition of operation;

[0051]FIG. 17 is a view similar to FIG. 16 of yet a further condition ofoperation of the device;

[0052]FIG. 18 is a side elevational view, partly in longitudinal sectionof yet another embodiment of the invention; and

[0053]FIG. 19 is a longitudinal sectional view taken through still afurther embodiment of the invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

[0054] A lancing device 10 (see FIG. 1) according to one preferredembodiment of the invention comprises an outer housing 12 having upperand lower portions 14, 16 connected together, and an inner housing 18fixed to the outer housing.

[0055] Mounted for vertical reciprocation in the upper portion 14 of theouter housing 12 is a cocking mechanism 20 comprising a pull handle 22to which is fixedly secured a hollow draw tube 24. Fixed to an innerwall of the draw tube 24 is a draw ring 26.

[0056] Situated within the draw tube 24 is a draw bar 30 having a pairof flexible hooks 32 at its upper end. The hooks are releasably latchedto a sleeve 34 which is movably disposed within the draw ring 26. A coilcompression spring 36 acts between a flange 33 of the sleeve 34 and aninner flange 38 of the draw ring 26.

[0057] A trigger sleeve 35 is mounted within the lower portion 16 of theouter housing 12. A lower end of the trigger sleeve rests upon a firstouter flange 37A of the inner housing, and a second outer flange 37B ofthe inner housing rests upon an inner projection 39 of the triggersleeve.

[0058] At its lower end the draw bar 30 frictionally holds askin-lancing medium in the form of a disposable lancet 40 in which aneedle 42 is disposed. The draw bar 30 includes a flexible latch finger44 that has a projection 45 adapted to be received in a hole 46 of theinner housing 18 (see FIG. 2) when the device is armed. A trigger member49 is mounted in a hole 47 of the trigger sleeve 35 and includes an arm48 extending partially into the hole 46. The trigger 46 includes aninclined cam follower surface 50.

[0059] A coil compression spring 52 acts between a top wall 54 of theinner housing 18 and a shoulder 56 of the draw bar.

[0060] Slidably disposed within a lower end of the lower portion of theouter housing is a firing tube 60 which includes an upper cam surface62. Fixed to a lower end of the firing tube 60 is an outer hollowstimulator member in the form of a cylindrical ring 64, having an endsurface 65 of generally frusto-conical shape so as to be oriented at adownward and inward inclination to generally face a longitudinal axis Aof the device.

[0061] Disposed coaxially within the firing tube 60 and outer stimulatorring 64 is an inner hollow stimulator member also in the form of acylindrical ring 66 having a frusto-conical end surface 67 also orientedat a downward and inward inclination.

[0062] The end surfaces 65 and 67 are of circular configuration whenviewed along the axis A, other configurations, such as polygonal, oval,etc., are possible.

[0063] A coil compression spring 68 acts between an upper end of theouter stimulator ring 64 and a downwardly facing shoulder 70 of theinner stimulator ring 66.

[0064] The inner stimulator ring 66 includes a lance stop flange 72adapted to be engaged by a lance ring 74 of the lancet 40 as will beexplained.

[0065] The first flange 37A of the inner housing rests upon a supportsleeve 80 which, in turn, rests upon an upper end of the innerstimulator ring 66.

[0066] In practice, when a fluid sample, such as blood or interstitialfluid, is to be taken from a user's body, a lancing device according tothe present invention can be used to minimize pain. To do so, a regionof the user's body having less sensitivity than, for example, afingertip, is selected. Such a low-sensitivity region could be theuser's forearm for example. Initially, the handle 22 is pulled up toraise the drawbar 30 until the projection 45 of the latch finger 44snaps into the hole 44 of the inner housing 18, as shown in FIG. 2.Simultaneously, the spring 52 is compressed.

[0067] If the outer stimulator ring 64 is pressed against the user'sskin S, e.g., on the selected forearm region FA, the ring 64 and its camsurface 62 are moved upwardly to displace the trigger radially inwardly,whereupon the projection 45 of the latch finger 44 is disengaged fromthe hole 46. Accordingly, the spring 52 expands to displace the drawbar30 downwardly so that the needle 42 punctures the skin sufficiently deepto cut capillaries in the superficial vascular plexus, as shown in FIG.3. Simultaneously, the spring 68 is compressed. The extent ofdisplacement of the drawbar 30 is limited by engagement between thelance ring 74 with the lance stop 72.

[0068] Once lancing has occurred, the compressed spring 68 expands toraise the drawbar, as well as the needle 42 and inner stimulator ring 66from the skin (see FIG. 4).

[0069] The user then alternately applies and releases a downward forceon the outer housing 12. Each time that a downward force is applied, theend face 65 of the outer stimulator ring 64 exerts a downward force Fwhich depresses a ring-shaped portion of the skin and body tissue whichis disposed in surrounding relationship to the wound or incision I,causing the wounded area to bulge while pulling apart the sides of thewound (see FIG. 5). Hence, fluid such as blood or interstitial fluid istrapped and pressurized so that it travels upwardly through thepulled-open end of the wound since the surrounding ring of depressedskin and body tissue restricts the outward flow of fluid. That action isenhanced by the fact that the force F is inclined inwardly toward theaxis A to force the fluid toward the bulged area.

[0070] When the downward force is released, the sides of the woundclose, and fresh fluid flows toward the area of the wound to replacefluid which had been forced upwardly through the wound. As the downwardforce is reapplied, the above-described action is repeated andadditional fluid is forced through the wound. Eventually, this “pumping”action results in the formation of a suitably large drop D of fluid(FIG. 6).

[0071] It will thus be appreciated that the present invention enables anample supply of blood, interstitial fluid or other body fluid to beobtained relatively painlessly from areas of the body which typicallypossess lesser amounts of such fluid as compared with the highlysensitive fingertip region.

[0072] Note that each time that the downward force is applied to theouter housing, the outer stimulator ring 64 moves upwardly relative tothe inner stimulator ring 66 so that the end surface 67 of the innerring 66 also contacts the skin surface S at a location inwardly of theouter face 65, thereby promoting the displacement of fluid inwardlytoward the wound. However, the present invention can be practiced by asingle stimulator ring arrangement 64A as shown in FIG. 8.

[0073] While the surfaces 65, 67 are continuous, i.e., non-interrupted,it may be desirable to provide either or both of those surfaces withcircumferentially spaced recesses 80 as shown in FIG. 7. The surface(s)65A, 67A will still depress a ring of body tissue surrounding the wound,but the areas of the ring corresponding to the location of the recesseswill be depressed to a lesser extent than the other areas. Those lesserdepressed areas will provide less resistance to fluid flow and will thusenable some fluid to leak past the ring, which would be beneficial inthe event that the user neglects to release the downward pressure on thedevice.

[0074] The stimulator member need not be in the form of a ring. Asdepicted in FIGS. 9-12, the stimulator member can be in the form of ahelical spring 90 formed by a flat strip 92. Such a spring wouldfunction in somewhat similar fashion to the double-ring arrangement ofFIGS. 1-7 in that a stimulator surface gradually comes into contact withthe skin in a radially inward direction to aid in propelling blood orinterstitial fluid toward the center axis. In that regard, FIGS. 9 and10 depict a condition when the spring 90 is uncompressed. In contrast,FIGS. 11 and 12 depict a condition wherein the spring is fullycompressed. Shaded regions in FIGS. 10 and 12 represent contact betweenthe spring and the skin. It will be appreciated that during compressionof the spring, the contact region of the spring progresses graduallyradially inwardly, causing blood or interstitial fluid to be pushedtoward the axis A and thus toward the bulged area of the skin.

[0075] Depicted in FIGS. 13 and 14 is yet another alternative embodimentwherein the outer stimulator ring 64B is interconnected to the innerstimulator ring 66B by levers 100 which are pivoted to the firing tube60B. Thus, upward sliding movement of the outer ring 64B is transmittedas a downward force to the inner ring 66B to slide the latter downwardlyand intensify the pumping action.

[0076] A further embodiment is depicted in FIGS. 15-17 wherein thefiring tube 60C has a carrier tube 102 affixed at a lower end thereof.Pivotably mounted on the carrier tube 102 is a circular array of levers104 each having an upper and lower end, each lower end carrying astimulator element in the form of a roller 106. Each lever 104 isrotatable about an axis extending orthogonally relative to the axis ofthe housing.

[0077] An inner ring 110 is slidable up and down, either by manualforce, or by a motor-driven cam (e.g., of the type disclosed later inconnection with FIG. 19). That ring 110 has a beveled cam face 112formed on its lower end. When the device is pressed against the skin,following a lancing procedure, the ring 110 is moved downwardly so thatthe cam face 112 engages rollers 108 mounted on upper ends of thelevers. Hence, the levers 104 are rotated such that the lower rollers106 are displaced inwardly and upwardly at a location disposed below theopen end of the bulged wound to open the wound and force blood orinterstitial fluid toward the wound to form a drop D. When the leversare not contacted by the cam face 112, the rollers 106 gravitate to arest position shown in FIG. 15. Repeated applications of the downwardforce cause the drop to become gradually enlarged as explained earlier.

[0078] Depicted in FIG. 18 is an alternative embodiment similar to thatdepicted in FIGS. 1-6, except that the lower end surface of the outerstimulator ring 64D is provided with a hollow stimulator element 114which is electrically connected to a battery 116 mounted in an upper endof the device. The element can be either an electrical resistanceelement (i.e., a heater) or a vibrator such as a piezoelectrictransducer, intended to stimulate fluid flow. A heater will expand thecapillaries and make the blood or interstitial fluid less viscous andthus more flowable, in order to increase the amount of the body fluidsample.

[0079] On the other hand, if the element 114 is a vibrator, such as apiezoelectric transducer, vibrations can be created which stimulate theflow of body fluid. This could be achieved by operating the transducerto produce frequencies below 28,000 cycles per second. Alternatively,ultrasonic frequencies, i.e., frequencies above 20,000 cycles persecond, will create interferometric wave patterns inside the skin thatcause contractions forcing fluid upwardly from the wound. Thefrusto-conical shape 114A of the end face of the element will optimizethe creation of such wave patterns. It may be further beneficial toemploy a heater, such as an infrared emitter, mounted in the housingwhich vasodilates the capillaries to increase blood flow. Anotheradvantage of the use of such frequencies is that only minimal downwardforce to the device may be necessary since the wave patterns may producean ample pumping action.

[0080]FIG. 19 depicts a device which is not automatically fired, butrather requires manual actuation of lever 130 against a bias of a spring132 to force a trigger 134 to push a projection 136 out of a hole 138(when the projection extends into that hole).

[0081] Mounted in a housing 140 of the device are a battery 142 andelectric motor 144 connected to the battery to be actuated thereby. Themotor 144 rotates a sleeve 146 about the axis A. The sleeve includes acam surface 148 which engages a follower roller 150 mounted on a tube152.

[0082] As the sleeve 146 rotates, the cam surface pushes the tube 152downwardly against the bias of a coil compression spring 154, to push aninner stimulator ring 156 repeatedly against a skin surface, therebypumping blood to the top of an incision in the same manner describedearlier herein. The inner stimulator ring 156 reciprocates along theaxis A within an outer stimulator ring 155. This embodiment eliminatesthe need for the user to pulsate the device up and down; the pumpingoperation is achieved automatically in response to actuation of thelever 130.

[0083] The cam mechanism 146 can be used in an automatically firingdevice, such as that disclosed in connection with FIG. 1.

[0084] It will be appreciated that the present invention enables asampling of blood or interstitial fluid to be taken from areas of thebody, such as a forearm, that are less insensitive to pain, despite thefact that those areas typically have relatively less fluid as compared,for example, to fingertips (which are highly sensitive to pain).

[0085] Therefore, there will be less reluctance on the part of users tohave a sampling procedure performed. For example, diabetics whoexperience a relatively high fear of pain will be less likely to neglectmonitoring their blood glucose levels.

[0086] Another suitable skin lancing device that can be used to practicethe present invention is that disclosed in concurrently filedapplication Ser. No. (Attorney Docket 018176-039), the disclosure ofwhich is incorporated herein by reference.

[0087] In lieu of using a lancet as a skin-lancing medium, otherskin-lancing media can be used, such as a laser, or known pneumatic orhydraulic injectors of the type which inject pressurized gas or liquidagainst the skin. Such auto injectors are sold by Becton-Dickinson, forexample, to inject insulin. By eliminating the insulin and merelyinjecting the gas (e.g., air or nitrogen) or liquid (e.g., water) atpressures above 30 psi. an incision could be formed in the skin fortaking samples of body fluid. Advantageously, small particles could bemixed with the gas to promote the tissue-cutting action. The particlescould comprise carbon particles of from 1 micron to 0.010 inches indiameter.

[0088] Although the present invention has been described in connectionwith preferred embodiments thereof, it will be appreciated by thoseskilled in the art that additions, deletions, modifications, andsubstitutions not specifically described may be made without departingfrom the spirit and scope of the invention as defined in the appendedclaims.

What is claimed:
 1. A method of obtaining a sample of body fluid from abody, comprising the steps of: A) applying a skin-lancing deice againstthe skin of a user to form an incision in the skin; B) removing theskin-lancing device from the incision; and thereafter C) applying aforce to depress the skin in a manner forming a ring of depressed bodytissue in surrounding relationship to the incision wherein a stimulatingmember and a plurality of levers act to bulge and stretch the incisionopen, whereby body fluid is expressed from the opening of the incision.2. The method according to claim 1, wherein forces between thestimulating member and the skin causes the stimulating member to retainthe skin in an stretched position.
 3. The method according to claim 1wherein step C includes applying the force in a direction inclinedgenerally toward the bulged incision.
 4. The method according to claim 1wherein step C comprises applying the force progressively closer to theincision.
 5. The method according to claim 1 wherein step C includesapplying heat in the region of the incision.
 6. The method according toclaim 1 wherein step C includes applying ultrasonic frequency to theregion of the incision.
 7. The method according to claim 1 wherein stepA comprises lancing a region of the user's body other than a finger tip.8. The method according to claim 1 wherein step A comprises applying alancet against the skin.
 9. A device for sampling body fluid comprising:a housing having an open end; a skin-lancing mechanism mounted in thehousing for applying a skin-lancing medium against a skin surface toform an incision therein, and then remove the skin-lancing medium fromthe incision; a plurality of levers mounted to the housing at the openend thereof for movement relative to the housing, the plurality oflevers pivotally attached thereto, wherein the levers cause the skinsurface to form a bulge in response to a pressing on the housing; and astimulator member mounted to the housing at the open end thereof formovement relative to the housing, the stimulator member extending abouta longitudinal axis of the housing the axis and adapted to engage theskin surface of the bulge and to stretch open the incision in responseto a pressing of the end face against the skin surface.
 10. The deviceaccording to claim 9 wherein the end face is inclined to generally facethe axis.
 11. The device according to claim 9 wherein the stimulatormember extends continuously about the axis.
 12. The device according toclaim 9 wherein the stimulator member includes circumferentially spacedinterruptions.
 13. The device according to claim 9 wherein thestimulator member is movable relative to the housing along the axis. 14.The device according to claim 9 wherein the stimulator member comprisesa first stimulator member, and further including at least one additionalstimulator member arranged in telescoping relationship to the firststimulator member, the stimulator members being relatively movable alongthe axis.
 15. The device according to claim 14 wherein the stimulatormembers include first and second stimulator members which are movablerelative to the housing and are interconnected to move axially inmutually opposite directions.
 16. The device according to claim 15wherein the first and second stimulator members are interconnected bylevers, each lever being pivoted intermediate its ends for rotationabout an axis extending orthogonally relative to the longitudinal axisof the housing.
 17. The device according to claim 13, wherein thestimulator member and the plurality of levers are movable relative tothe housing and a interconnected to move axially in mutually oppositedirections.
 18. The device according to claim 9 wherein the stimulatormember comprises a helical spring.
 19. The device according to claim 9further including a second stimulator chosen from the group consistingof, a heating mechanism for heating the stimulator member or levers, avibrator mechanism for vibrating the stimulator member or levers. 20.The device according to claim 9, wherein the plurality of levers arecircumferentially disposed about a distal end of the housing, whereineach lever pivots independently.